// random.cpp

/*    Copyright 2012 10gen Inc.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

#include "tbcore/util/random.hpp"

#include <stdio.h>
#include <string.h>

#ifndef _WIN32
#include <errno.h>
#endif

#define _CRT_RAND_S
#include <cstdlib>
#include <iostream>
#include <fstream>

TB_NAMESPACE_BEGIN

// ---- PseudoRandom  ----- //

int32_t PseudoRandom::nextInt32() {
    int32_t t = _x ^ (_x << 11);
    _x = _y;
    _y = _z;
    _z = _w;
    return _w = _w ^ (_w >> 19) ^ (t ^ (t >> 8));
}

namespace {
    const int32_t default_y = 362436069;
    const int32_t default_z = 521288629;
    const int32_t default_w = 88675123;
}

PseudoRandom::PseudoRandom( int32_t seed ) {
    _x = seed;
    _y = default_y;
    _z = default_z;
    _w = default_w;
}


PseudoRandom::PseudoRandom( uint32_t seed ) {
    _x = static_cast<int32_t>(seed);
    _y = default_y;
    _z = default_z;
    _w = default_w;
}


PseudoRandom::PseudoRandom( int64_t seed ) {
    int32_t high = seed >> 32;
    int32_t low = seed & 0xFFFFFFFF;

    _x = high ^ low;
    _y = default_y;
    _z = default_z;
    _w = default_w;
}

int64_t PseudoRandom::nextInt64() {
    int64_t a = nextInt32();
    int64_t b = nextInt32();
    return ( a << 32 ) | b;
}

// --- SecureRandom ----

SecureRandom::~SecureRandom() {
}

#ifdef _WIN32
class WinSecureRandom : public SecureRandom {
    virtual ~WinSecureRandom(){}
    int64_t nextInt64() {
        uint32_t a, b;
        if ( rand_s(&a) ) {
            abort();
        }
        if ( rand_s(&b) ) {
            abort();
        }
        return ( static_cast<int64_t>(a) << 32 ) | b;
    }
};

SecureRandom* SecureRandom::create() {
    return new WinSecureRandom();
}

#elif defined(__linux__) || defined(__sunos__) || defined(__APPLE__) || defined(__freebsd__)

class InputStreamSecureRandom : public SecureRandom {
  public:
    InputStreamSecureRandom( const char* fn ) {
        _in = new std::ifstream( fn, std::ios::binary | std::ios::in );
        if ( !_in->is_open() ) {
            std::cerr << "can't open " << fn << " " << strerror(errno) << std::endl;
            abort();
        }
    }

    ~InputStreamSecureRandom() {
        delete _in;
    }

    int64_t nextInt64() {
        int64_t r;
        _in->read( reinterpret_cast<char*>( &r ), sizeof(r) );
        if ( _in->fail() ) {
            abort();
        }
        return r;
    }

private:
    std::ifstream* _in;
};

SecureRandom* SecureRandom::create() {
    return new InputStreamSecureRandom( "/dev/urandom" );
}

#elif defined(__openbsd__)

class Arc4SecureRandom : public SecureRandom {
public:
    int64_t nextInt64() {
        int64_t value;
        arc4random_buf(&value, sizeof(value));
        return value;
    }
};

SecureRandom* SecureRandom::create() {
    return new Arc4SecureRandom();
}

#else

#error Must implement SecureRandom for platform

#endif

TB_NAMESPACE_END
